Exercise-induced hypoalgesia with end-stage knee osteoarthritis during different blood flow restriction levels: Sham-controlled crossover study

Abstract

Background: Blood flow restriction (BFR) training could be a valuable treatment to induce exercise-induced hypoalgesia (EIH) in patients with end-stage knee osteoarthritis. However, the use of BFR in these patients is poorly explored and there is no evidence about the training dosage needed.

Objective: To evaluate the effect of resistance training protocols with different occlusion levels of blood flow restriction (BFR) on EIH in patients with end-stage knee osteoarthritis.

Design: Crossover study.

Setting: University physical exercise laboratory.

Participants: 26 adults with end-stage knee osteoarthritis.

Interventions: Patients performed four sets (30, 15, 15, and 15 repetitions) separated by 1-minute rests of three protocols/sessions of low-load (30% one-repetition-maximum) seated knee extensions with elastic bands and BFR: placebo (sham BFR), BFR at 40% arterial occlusion pressure (AOP) and BFR at 80% AOP.

Main outcome measures: Pressure Pain Thresholds (PPT) and Visual Analog Scale (VAS) collected before, immediately after session, and after 10 minutes.

Results: No differences in EIH were found between the different levels of BFR. However, 80% AOP protocol worsened VAS scores immediately (mean difference [MD]: -21.2 (95% confidence interval [CI] -33.9 to -8.5) while improving PPT immediately (MD affected limb: -.6 [95% CI -1.1 to -.2]); contralateral: -.6 (95% CI -1.0 to -.2]) and at 10 minutes (MD affected limb: -.6 [95% CI) -1.2 to -.1]; contralateral: -.7 [95% CI -1.1 to -.2]; and forearm: -.5 [95% CI -.9 to -.05]) post-exercise compared to baseline.

Conclusions: There is no EIH difference after using different occlusion levels. EIH is modulated by pain-related psychological constructs and self-perceived health status.